SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aaad4d70de37285e4338290726821d8a00821b48c00a2ebaad1edd627356bfaa' 
  AND token = 'rsvSf9/HwN8qGlrZE008p039Fj53dUnRK4L2iGcfRns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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