SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '48ac88ae111114ecc8f02b0460f496f886b248ed583a0917589297b92f979438' 
  AND token = '0v+EHhkbGaRhWuORxAw5bsshPL3+5AsV+TbVfq3JPKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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