SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20bb91f3d98ed6d2d45bcd8f712a579342f8f7c4ccd564a3955cdaa1a5103506' 
  AND token = '4/iLjuHykBufVChzm7D6GgGSqzvDadtSw7CJ6f9oQ28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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