SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5213a0f947ac8afd518e05c585c69d1429f598be8edf17aa330894da6e030709' 
  AND token = 'iUS+brk1vBf6UL5n5ZTG5OnEGzSetdlNeYuOQuldFp4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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