SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f84a446f17a739f0b22c1ddfab87b9dedb5c92178bddd7b3ebc547f88e345eeb' 
  AND token = 'simIi+ARN5oMgt+mR+ScYwhuxHyHkTLgK0QHq9uQ+Vw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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