SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df75ad98ec5312979edeaeb98a11550683b825ddd68a82860042c629fdde3674' 
  AND token = 'lAbHGNJ+q4wSQ2VxlNb0h9XjJsop9loh/35snU+fbUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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