SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4128a21ff3a7541be29487890ef6be91f2f8ced4e5668466a440f939827f9d9e' 
  AND token = 'yWvL90McG+uv2qDqqpmZkJmLIaEHtCPKedsW2iz1Euw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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