SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78f737d90b63d2e5c0e472a4c3edc599b96ef8c75128dde7c7a65aa5a54b3fc0' 
  AND token = '+LqwtfxAFYFiYPbmVLd/9pZ5zSewkBT+J1L5s0HA1j4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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