SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6526e8820edfcf77b8b6c1da2c7c08218aa02a0c2c6bdaa87ebae6d244c3be2f' 
  AND token = 'E94VmLbXLdb7XUoI5T8+YRdHNGFHYB+MmTySIWjuB48=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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