SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e34c58ac559f28e5999d948e61ac9ac9bc9bc8c2b589b185320dcb6adb5be1f' 
  AND token = 'jcch/W1zvqJXlitKPdE9LnLPm3kmMpvLVhmSTiN+rvc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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