SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7e1e4bec79decc7fa697ea8875c20210b5ab8c421d6ec013b8ae2cd900b2fee' 
  AND token = 'Pn2VAQRSYgOvRJ6yhFoVuP5NLeURQFvSKiDYgcb/iDM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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