SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '667866301cb219ab25af941a65b06541c8613933c7b11fc541f2dcb44d9ee251' 
  AND token = 'zbJCy2xlk7orcrfTxisGsveo+Lr58ynRMWpgiOAAsAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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