SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b66e813d422fd511429650a068b936134093e22c8ba3ca70b698c9c277cd2c7c' 
  AND token = 'Ejkk8f8UTZmCBlGmev49QCe8wpX/K21MaUf+slwz66U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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