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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fee928dd9bcc62649483c42c24b75c527ef9b9be59e3a97da408e54401afaa5a' 
  AND token = 'FmyDt0mjGGFxYklGp0HTwoSf8cyYp2IQ6yUDsJW+Hc0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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