SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4c8afa0940a94387db92cd5299ca6c4c7f95535ae950e197588872d0f7ae29f' 
  AND token = 'q6Rly/dVnjT4UxZ3yV21KOLaJkpzF66HQDErKp3mrhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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