SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '342db5c96c8a9f3d78dc484dc65c9e373058074be09f66c20805a95637ed2ef3' 
  AND token = '6Av0Ln24yu8AbYFFysh8axDVwFatogSKgKQa29GtfAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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