SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bcf45a68dea2dba7d1c09a11d4e66e9a9503b848516f282500895bbd7249e1f' 
  AND token = 'zxuBIxqjBrCXEWjIUiJeNMcVi9PVQS+8r2C6vWUE5qc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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