SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6128afffebfa16d562f6c45188dc914c9804d8cfb85c538bf32898469db72f40' 
  AND token = 'jeZhGgCd1v0CPEY2KOyRyV5BUmifheRvs6Z5BgQhXFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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