SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b47b8b56efd2c080cef60406c6c3c7bb349c146dca01feb182fc5d91d8af3423' 
  AND token = 'faslTLCL2QLy6PkSbbtg8uTHrKmoOXPj9xsmoHV1j7g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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