SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd412f54b3ab8550a6c51cc845b99fa4014c823b6492b1347ceb3238a5cfb5d23' 
  AND token = 'dzJ3OovT6Gt/ZRP9P+Gl9KPAnqYUJ2gjr1i3DJlFtlM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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