SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16cd21a5fe6d3b65860e2b429669b5086bdf1dd58fe0771743c7d989383c9984' 
  AND token = '+z3B0GeC3TxalmjJQIGPjfu4WaU59KRXqVXp08I5as4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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