SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f9f05a66831a94821a4484d4b76f57b68655d4131cffb1514212dcb47219528' 
  AND token = '6TNHIRYJCmkhqceK2UVllucbAR5wKl6BNRB9gAzIsOI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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