SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b96233a491c02e31985a13fcb57e004019397d5fbdcad26270e06b82cdaf74b5' 
  AND token = 'OsEJXV9/6pXW12/fQfvH8kL06ZZ/vZGIGqLObKTHKKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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