SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a107c5d4d0a7153665558c2076167c364fba7b49da88a53438112b95585d636a' 
  AND token = '6OMZc57801LFaTgRmFLlHBsJBHTgAubp6vZbc+GAPis=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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