SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87251126f6f971515b3007ae45dd43cd364d74a836ca3ade2f2890f441b34aec' 
  AND token = 'B9hl6SPi3dXkVVK8WmRZ2235OA+YrmzUwEgYVkUtfNI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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