SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e27c887b2313e967361ee4edae19cd76e22acd2c68d253541d28e71e4e4933fc' 
  AND token = 'uWdep7VBuiqq/ElopAkbpSFeu288PfD2ZktGw5FcDLY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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