SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd03cbfc904a618e8a059d31dc5e24fa01a01b92fb22e2364a2ba40da7b327a8e' 
  AND token = '+sen+LkpP8TY2hjS35NSEftV/aClanTpqEZQOgTREPE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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