SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68a24e5ef0c2cc735e4e9c4159380bbf15a294d641da6e792b5453843724781b' 
  AND token = 'CmSWZBrVOmctcI7qtWrJ3sf24qJBdDgPs7ClCM9uAL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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