SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b557ac0f46076cf456d5d39f0a20ed1779b2417af65a9a9373cb981d4804096a' 
  AND token = '6fet27PHlMXbOO8GTOafYGhgbrbdhyaKudVNqB783eo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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