SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '10c6b46618d610caa00c4068660c59a91a23aa81d335b4861c96272775ff3e74' 
  AND token = 'siImDZx0PPF5PL4BJOlutBKDy+NlQiA8U+fXfCrI8Gw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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