SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3850454325ff30de8e24875f2858ef414feccbea6c44451fbcbd4f47b91760a1' 
  AND token = 'nMwt9kWheyB1QeJljQ6gt4T1HRRT2xohBJQaCxio5oI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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