SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d8aaa2c3acaaeb38eedade39338464289592611bc73bf29277b725aa32e88c4' 
  AND token = 'kKD1Gye52BJTdErhbRKZ82pmLxGfyiYDAtFUm3R31r8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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