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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd752b0f27fa1c5b395c5ba8b7049ce70d9bd40a9c1ffee6a4db0b3b71fbf559a' 
  AND token = '8ec3YiNg92sMQRlDC+99EjMrk/nHOyK/RyimoAFUpdU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}