SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c491bb8b3acc21fc7dc19ddebb32d41098a69aaa24dc0dc8af104cffde2a6b9b' 
  AND token = '2ZT/tYzX0NQNL2DEH3F/JqIRry/aWltLB4hpwpIlxVw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}