SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f374c380660cf4fa40f8d7269fbc9913f09f142236e327842a913b79c58ab270' 
  AND token = '3p5UjadaKDjtcHgrzNtpvqMU77mKSpPLyzKgxleKHWU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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