SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c2caf518d3647462d9b847781bd3cc0a2b896f1674a2cbacc53b7970de5263e' 
  AND token = 'dumccLKGKY/pSzlMXwVRWvSKNJU38pItEywJBigL8tA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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