SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3669644cc5278266d0c219446344b8ba79c7ca843126f5c8ff1979756be45530' 
  AND token = 's99XpEGLo/SObqpl2ey1S4vQZDzgShAh/xpxLjHL8WI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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