SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '15871150cfffbb4835e016c63190a316d71b600fda38d98fc448e9d0a574e254' 
  AND token = 'm37MHL5wGXm7vYkxZ66YBDq1HfPNMKLkrn2Amsgk1yA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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