SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bb1cb6c78403a86badfa8c12c08689acee3587dfe739e9498ca79f1b1f98790' 
  AND token = 'uJj2tHDxsdavdvUKzuQFuS2cDgG3m2HoQ8wHJWoyrBo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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