SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68a81065b62ac37a6d19909c30a23a92e2a1ee1cc9c44d0d321129de11a06af4' 
  AND token = 'PSU0dMByBnDYTdecwH0fWLsi013/dShQmm/2VdiIQ+8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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