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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4a3c8b5e8e01f61cdda0b874ab1cb08f71470734ba0b32a6f2955ccbb141b77' 
  AND token = 'HJqxh6MNYn+dMIlNKYzAzNh+XF+FDTjDRDli6L/ffNw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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