SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0ac4c20990d7e43ee1919df9037edee065633963396519116c298af56474cee' 
  AND token = 'n/eQGoJEWN8z2F7fAAeQ899NQP+OLseRg71M9ekzlso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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