SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b222d7242d36eaad28f7c132086209b94bf3bb34bff98413da3a3383e0da38f6' 
  AND token = 'j8e+OV7BiPwJ2peQci5mfFNWYDxo04U4fFfyjChVCzM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}