SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e52040279266917afa05cd477c6f4ab497a6d149a1da142aa525dc353f490f88' 
  AND token = 'Xf4Zf6GIQjtExwkXVdFYbmY+GLlCvSrCVG1tYPDqE6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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