SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f44afb811a0099c3d10c7766e0773005f53d9690371c3393bce702621cdf00c' 
  AND token = 'n6Epers18eoTCFmgbHMjJGVXAuExy1CtQWViFP+HjlM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}