SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51d32183d6c312b4bfb4390362e21a5281c02c9cd96864e09f382a8186e94fef' 
  AND token = 'W1Ax2ACxoNJHT1JdoONG+803l31D0YhokdkZkY0zr3A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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