SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1558cca3fb16757ba594f9675e114b7150475938b3f4ce1693da8029682d903b' 
  AND token = '5HMsdjXRzZWiu6y3YnQmeJW+SpCF5CknvbvU7faKUeU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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