SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75f8bd82b0b414e5686a851173aeaef6dacf8998f55b9849a1c48f0aab08639a' 
  AND token = '0vEKVinh2dFeOPj/j66JOIvF/U9Vxuq0NM+ZVrP4KKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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