SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '521d94671341659a8cb7d2843271bf3a5f1565cf3da5f8547fbdd0f6b98ea3e2' 
  AND token = 'z9YJmE72FtVuZWeSyiq46unvTvU9qDKnyQExxJ+f71k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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