SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b547c2291b1e40afc6b37c6d13d0b43e920f151b4aeb46e4f22979ccfa7d92ca' 
  AND token = 'Id6euuE0TBCcuUkXR7eUDyYonrcpHua3diCGkZ2QHzM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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