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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ec9e88fc86412a50cebbdfec1df37ff0200c8388b7d6c8a76cc640196f4fabbd' 
  AND token = 'WeTHJjcWqFAOnEV1Gqjd8USpDxlio9Z8XwIweG7gGpU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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