SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2671093dfe0be46becd20abf912bc68fc7e29604aa4422d874fefcebfcb85ca7' 
  AND token = 'xXJnCXviQGoNQpaMWjFbiybrG/p1VDaMU0FHll+0CAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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