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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3db170cc1a9c81e3f98c60b38581c06d6193f1817fa1581c618d6d5267c1c26' 
  AND token = 'JclWiRnG7aJZWRGfDWQVvbrnVpbIXc1dN0IxHZDFmCU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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