SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f2fd6f6c40c69041604adf68fe6334df3d68f01400377ba23f508e96bde411d' 
  AND token = 'pSc9zwaonQ3lY4TbBOJpmxeSe56lafJjupphdekHtvc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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