SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b186af741be203f35eb7900cc129e295e5a6927ea9cced0c04a0cf51a407688e' 
  AND token = '5GjUXz1Jnz+RJyZh+zl3gHDDGqbYUgCvL5UQRrpY6tQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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