SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '923c1fe5e1829f05957f7fc7cbd1c64062504cc1fea51dc2705e281d78900891' 
  AND token = 'fBUEnuxCaHbmAAMt8UsUeAUH3GkuFOD5JFT/jyoY67Q=' 
  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"
    }
  }
}