SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83eaa173742de14e6bb2b6be6d60361fdcaf0ffc7b58844c29b28e2827a94145' 
  AND token = 'MPH5ScpakimsWUgJECe/9ADt02cZRxMxPhI596semoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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