SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '58df8a2bc77b15a91123dbd08b1343efdba1685ac83c60c20776bf3d49eb3125' 
  AND token = '3U/28JrsXgCUfFz9Y+ckkcge+S955715xWT2pjbHp+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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