SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0681375ad73173ea884f67eeecd305eca65d323501d135bab804b29ad303872' 
  AND token = 'aIUn9K2SdZlxIOkCV0HdDSVtHlHORMAd7ugHEwve1uk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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